1. Technical Field
This invention relates to shroud devices that are used to maintain neutral atmosphere around a molten metal stream to prevent contamination from outside atmosphere required in high quality metal production.
2. Description of Prior Art
Prior Art devices of this type have used a variety of different shrouding configurations to shield and isolate molten metal streams in a neutral atmosphere during transfer from a ladle, see for example applicant's own U.S. Pat. Nos. 4,840,287 4,527,718, 4,555,050 and 4,316,561.
In U.S. Pat. No. 4,840,297 a shielding apparatus is disclosed that provides a seal between a metal wear assembly on the ladle and a runner trumpet.
In U.S. Pat. No. 4,527,718 a shielding device is disclosed with a support housing having a ceramic ring positioned therearound. Inert gas supplied to the support housing by an inlet pipe and a seal is achieved between the housing and the insert and the ladle respectively.
In U.S. Pat. No. 4,555,050 a closure device is shown with a gas seal. A conical discharge nozzle is inserted into a shielding tube having an interior registering conical surface. Inert gas is delivered via an annular recess within the shielding tube to form a gas and mechanical seal therebetween.
U.S. Pat. No. 4,316,561 is directed to a latching apparatus to support and position a pouring tube shroud from a metallurgical vessel. The device has an elongated arm configuration with a tube engaging fitting and release mechanism allowing the support and placement of the tube shroud during pouring.